It is crucial for healthy joints to have intact and functional menisci to prevent osteoarthritis. This project strives to create a replacement meniscus from a biphasic polymer composite as a potential surgical solution for meniscal injury. To accomplish this, nylon fibers and polystyrene - polyethylene oxide diblock copolymer with a terminal hydroxyl group will both be chemically modified to create a composite fiber-reinforced hydrogel that will be further modified with a photopatterned interpenetrating hyaluronan (HA) network. It is hypothesized that controlling for copolymer composition, fiber density, and HA tie line density will result in material properties similar to those of the native meniscus. Furthermore, it is hypothesized that this biphasic polymer composite can be molded into a 3D meniscal construct with similar pressure distribution properties as the native meniscus and will protect the underlying cartilage in an in vivo large animal model. Eighteen variations of the biphasic polymer composite will be created and mechanically tested to optimize the material properties for in vivo performance. Compressive, tensile, shear, recovery, fatigue and tear tests will be used to compare the 18 variations. Magnetic resonance images will be taken of sheep knees and used to construct a 3D mold. The fibers will be aligned circumferentially with ends extending past the main body for use in tibial attachment. The pressure distribution properties of the top four optimized 3D constructs will be compared to the intact native meniscus, the joint following a meniscectomy, and the native meniscus reattached through bone tunnels. Peak pressure, mean pressure, location of peak pressure, and contact area will be determined using Tekscan pressure film. Finally we will evaluate the ability of the construct to protect the underlying cartilage in an in vivo large animal model. If the goals of this project are met there would exist a biphasic polymer composite meniscus that mimics the mechanical and functional properties of the native human meniscus. This meniscal replacement could provide a revolutionary addition to the field of osteoarthritis and meniscal injury.